1. Field of the Disclosure
The disclosure relates in general to material testing systems, and more particularly, to an extensometer assembly for use in association with material testing systems, and in particular, polymer material testing systems.
2. Background Art
The use of extensometers is well known in the art. Generally extensometers are utilized in association with materials testing systems. Typically, a single extensometer or pairs of extensometers are positioned about a test specimen. When a load is applied to the test specimen, the extensometers measure strain and/or displacement, that is, a physical change in the dimension of the specimen about the location of the extensometer. Generally, such measurements are measured by the sensor and then recorded or logged and processed by processing equipment (such as computers).
With testing of polymer materials, additional considerations are presented. Specifically, as polymers are generally much lighter than metals, the weight of the extensometer becomes a more critical factor. While it is important to address the weight and mass effect of the extensometer, the extensometer requires compliance, as stiffness of the extensometer would undesirably affect the accuracy of the extensometer. Additionally, it is important that the relative movement of the displacement arms occur in a frictionless environment so as not to introduce additional variables. Furthermore, it is often difficult to position sensing equipment in a position that allows for displacement of the arms without affecting the specimen.
Additionally, it is often the case that different extensometers must be utilized when obtaining displacement measurements in the direction of force application and in a direction perpendicular to the force application. Often the manner in which opposing extensometers are coupled limits the use of the extensometer to either one type of measurement or another type of measurement.